In trolley traveling winches of gantry cranes of the above-mentioned type without direct trolley traveling drive, the trolley is moved by at least one motor-driven cable drum, which is arranged in the machine housing of the gantry crane.
In gantry cranes for container, grab, or general-cargo operations, one cable pair usually extends from the dram in the machine housing to the water-side jib end, and one cable pair extends to the land-side support end. The cables are deflected there and extend to the trolley. The cables extend at different heights, i.e., deflection in the area of the fulcrum point of the jib is highly complicated during the retraction of the jib, especially in order to keep the necessary tensioning path of the cable due to the jointly swinging cable rollers short. Supporting the cables to reduce the sag is possible only in a mechanically highly complicated manner, and it leads to increased wear on the traction cables for the trolley because of the multiple additional deflections of the cable.
Since the cables run off from the drive drum under the machine housing platform, i.e., the drum projects below from the platform, the installation position of the drum and transmission is unfavorable, especially from the viewpoint of maintenance.